Camera

ANATOMY OF A CAMERA

There are many different types of motion picture cameras of varying
sizes that serve a variety of purposes, but all cameras have the same
basic structure. The basic components of a camera are photosensitive
film, a light-proof body, a mechanism to move the film, a lens, and a
shutter. Most cameras have a number of other features, ranging from
viewfinders to detachable magazines to video assists, but the basic
elements are the same in all cameras (save for those of the digital
variety).

The film used in modern motion picture cameras is very much the same as
the film that was developed in the 1880s and 1890s. It consists of an
emulsion bound to a flexible, transparent base. Until 1951, the base was
made of cellulose nitrate, a highly unstable substance that was prone to
fire and decay. Since the 1950s, films have used a nonflammable safety
base, usually of cellulose triacetate (acetate) or a thinner and more
durable synthetic polyester base. Along with the emulsion, the filmstrip
contains perforations on one or both sides, used to pull the film into
place in front of the lens, and sound film has a strip along the edge
containing the soundtrack.

The film is housed in the magazine (A), a detachable, light-tight unit
that attaches to the camera. Unexposed film starts out on the supply
reel (B), and after winding through the camera the now-exposed film ends
up on the take-up reel (C) in a separate compartment of the magazine.
There are different types of magazines for motion picture cameras. In
the most common type, the displacement magazine, the supply reel sits
directly in front of the take-up reel in an oval-shaped compartment on
top of the camera. Coaxial magazines mount on the back of the camera and
situate the two reels parallel to one another. Coaxial magazines are
less widely used than the displacement type, but can be useful because
their lower profile makes it possible to shoot in smaller spaces.
Quick-change magazines contain parts of the camera mechanism in the
magazine itself, making the magazine heavier and more expensive, but
allowing for faster film changes. These magazines are generally the
rear-mounted coaxial design. Magazines hold different amounts of film,
depending on their size. Magazines for 35mm cameras most often hold
400-foot reels (four minutes at twenty-four frames per second [fps]),
1,000-foot reels (ten minutes) or 2,000-foot reels (twenty minutes). The
standard reel size for 16mm cameras is 400 feet (eleven minutes at
twenty-four fps), but other sizes are available.

A drive mechanism, or motor, pulls the film from the supply reel in the
magazine and feeds it past the lens and aperture. With the exception of
Edison's Kinetograph, which used a battery-operated motor, early
cameras were cranked by hand. This practice resulted in irregular film
speeds and potentially inconsistent exposure times, as frames were
stopped in front of the lens for varying amounts of time. The
introduction of electric motor drives meant that film could run through
the camera at a consistent pace of twenty-four frames per second. Motor
drives on modern cameras can also provide

Cutaway view of a reflex movie camera.

variations in speed, useful for producing the effects of fast motion
(by reducing the film speed) or slow motion (by speeding up the film).

Just before the film reaches the area in front of the lens it makes a
small loop, known as a Latham loop (D). The Latham loop was developed by
the Latham family (Woodville Latham [1837–1911] and his sons Gray
and Otway) around 1895 as a way to prevent film from breaking as it
worked its way through the camera. By placing a loop above and below the
lens, stress on the film is redistributed, allowing for longer films
with less breakage. Once the film passes the Latham loop, it is pulled
into place in the film gate by the claw. The claw advances the film
using intermittent motion, and holds it in the film gate while the frame
is exposed to light. The film gate (E) consists of two plates that help
hold the film during exposure. The front plate, which has a rectangle
cut into it to allow light onto the film, is called the aperture plate.
The edges of the rectangle, called the aperture (F), form the border of
the film. The rear plate, which holds the film flat, is called the
pressure plate.

For the fraction of a second that the film is stopped in the film gate,
the shutter opens to allow light to pass through the lens (G) and
aperture and onto the film. The purpose of the lens is to focus the
light rays from the scene in front of the camera onto the film. There
are two basic kinds of lenses: prime lenses, which have a fixed focal
length, and zoom lenses, which can change focal lengths. The focal
length refers to the size of the lens, and affects how the image will
appear on film. Lenses with focal lengths of less than 25mm, called
wide-angle lenses, take in a wider area than telephoto lenses (lenses
longer than 50mm), which can shoot objects at greater distances but
provide a narrower shot. Camera lenses are also classified according to
how much light they let in, also known as the lens speed. Lens speed is
described in terms of f-stop or t-stop ("t" for
"true" or "transmission"), with the smaller
number f-stop or t-stop letting in the greatest amount of light, and
therefore signifying faster lenses. The lens is attached to the camera
on the lens mount; some older cameras use turret mounts, which feature
three or four prime lenses of varying focal lengths that can be rotated
into place.

Thomas Edison's studio, the Black Maria in West Orange,
New Jersey.

While the film is stopped in front of the lens, the shutter (H) opens to
allow light to enter through the aperture. After the film has been
exposed to light, the shutter closes and the film advances to the next
frame. If the shutter is not completely closed before the film starts
moving, the image will be blurred. The most basic shutter is in the form
of a rotating disc, and the standard shutter speed, or exposure time,
when shooting at 24 fps is 1/50 second. Some shutters are variable, and
can be adjusted to allow longer or shorter exposure times. Once the
shutter closes, the exposed film advances, continuing past another loop
beneath the film gate, and finally ending up on the take-up reel in the
magazine.

The camera operator is able to see what is being recorded by looking
through the camera's viewfinder. Most cameras today use a reflex
viewfinder, which allows the operator to see through the camera's
lens, also known as the taking lens. Older cameras employed a nonreflex
viewfinder, which used a separate lens and was therefore less accurate.
Viewfinders work by using a series of mirrors to divert light from the
lens to a viewing screen, which displays information crucial to the
camera operator, such as the outline of the frame. An alternative to the
viewfinder is the video assist, or video tap, a device that allows more
than one person to view the image from the camera. The video assist is
similar to the viewfinder in that it diverts light from the taking lens
and sends the picture to a screen, in this case a video monitor that can
be set up near the camera. The quality of the images and color on the
video assist monitor are inferior to what is actually being recorded by
the camera, and therefore the video assist is not used to gauge what the
final product will look like. Because it is not attached to the camera,
an important use of the video assist is for crane or Steadicam shots, or
any other shots for which the camera operator is unable to look through
the viewfinder.

While all cameras operate in essentially the same way, the size of the
filmstrip varies depending on the camera type, which affects the size
and shape of the projected image. There are four film gauges, or widths,
that are standard worldwide: 8mm, 16mm, 35mm, and 70mm (the numbers
refer to the actual width of the filmstrip, in millimeters). These
gauges are used for different purposes and yield different image types
and quality. The larger film widths provide better quality images
because they offer larger frame sizes that afford more room for detail.
However, as film formats increase in size, they become progressively
more expensive to use, and the equipment becomes heavier and more
cumbersome. The standard professional film gauge, used in most feature
films, commercials, and television movies, is 35mm. This is
approximately the size that was used in Edison's Kinetograph and
the Lumière brothers' Cinématographe, and it has
been the most commonly used size throughout cinema's history. In
most movie theaters projectors require 35mm film.

In the 1920s 16mm film was introduced, with the goal of providing a less
expensive alternative to 35mm film. Because the size of the frame of
16mm film is about a quarter the size of 35mm film, the image is not as
sharp. However, 16mm cameras are significantly smaller and lighter than
35mm cameras, and their portability makes them ideal for documentary
filmmakers, news reporting, and amateur filmmaking. The 16mm camera is
also frequently used by avant-garde and experimental filmmakers, who
appreciate the format's portability, low cost, and overall
flexibility. The size and weight of 16mm and 8mm cameras allow freedom
of camera movement and eliminate many of the constraints involved with
35mm shooting, and the grainy quality of 16mm and 8mm film stocks can be
manipulated by experimental filmmakers to create interesting effects.
Because of their versatility and ease of use, then, both the 16mm and
8mm formats have long been favored by filmmakers working outside the
mainstream.

Long popular with amateur filmmakers, 8mm film was originally introduced
in 1932. Because it was created from 16mm film split down the middle,
8mm film has sprocket holes along only one side of the filmstrip. Super
8 film was created by Kodak in 1965, and, like the Super 16 film
developed in the 1970s, is able to record a larger image on each frame.
Due to their low cost and easy to operate handheld cameras, 8mm and
Super 8 were, for many years, the formats most commonly used in home
Cine and amateur movies, although their popularity has since been
eclipsed by video and digital video.

The largest gauge in use is 70mm, which offers beautiful details and
clarity, but is extremely expensive to shoot. Film that is described as
70mm uses 65mm for the image and perforations and 5mm for the
soundtrack. Frequently, films that are projected in 70mm today are shot
using anamorphic lenses, which compress the image to fit on 35mm film,
and then decompress the image during projection to restore it to its
original size. The 70mm format can increasingly be found in amusement
parks, as part of 3-D attractions such as Walt Disney World's
Honey, I Shrunk the Audience
or rides such as Disneyland's
Star Tours
. IMAX films, the largest format in use today, make use of 65mm film,
but position the frames horizontally on the filmstrip, rather than
vertically.

A wide variety of cameras are available to filmmakers, depending on
their needs. Bolex offers student, independent, and amateur filmmakers
low-cost, high-quality 16mm and Super 16 cameras known for their
versatility. In 1937, Arri introduced the first 35mm camera with a
reflex mirror shutter, which allowed the camera operator to focus and
frame a shot using the viewfinder. Arri produced a professional 16mm
camera with the same reflex mirror shutter in 1952, and Arri cameras
have since become the industry standard for 16mm filmmaking. The French
Éclair 16mm camera is quiet enough to allow for synchronous audio
recording, and light enough to allow for easy handheld operation; it was
used frequently by
cinéma vérité
and New Wave filmmakers in the 1950s and 1960s. Mitchell cameras,
introduced in the 1910s, were known for their steadiness and
reliability, as well as their special effects abilities. Mitchell
cameras were also used extensively in 65/70mm widescreen production.
Panavision provides 16mm, 35mm, 65/70mm and digital cameras and lenses
that have been widely used in Hollywood feature filmmaking since the
1950s.

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